反復充放電循環過程中碳包覆SiO和鋰摻雜碳包覆SiO的結構和相變的比較

 

摘要

碳涂層SiOSiO-C)是一種高容量的負極材料,在初始充放電循環中會經歷明顯的容量下降。相反,最近開發的摻鋰的SiOCLiSiOC)的電容降明顯較小。為了解釋這種差異,我們通過比較它們的Si結構和從固態幻角旋轉核磁共振和Si K邊緣X射線吸收獲得的電子狀態,對與這些材料的充放電循環相關的結構和相變進行了詳細的研究及精細的結構測量。結果表明,在SiOC的情況下,充電過程中產生的Li4SiO4在初始充放電循環中的放電過程中會部分分解。這些生成和分解行為在前20個周期中最為強烈。我們認為,這種現象是在SiO-C初始循環中觀察到不可逆容量增加的原因。另外,我們證實,LiSiOC的成分Li2SiO3在電化學上相對穩定,盡管其中一些在充放電循環中逐漸轉變為Li4SiO4。一開始就存在Li2SiO3,這意味著與SiOC相比,充電過程中生成的Li4SiO4更少,我們相信這可以解釋為在LiSiOC的初始循環中容量沒有明顯下降。


期刊摘要原文:

Comparison of the Structure and Phase Changes of Carbon-Coated SiO and Li-Doped Carbon-Coated SiO During Repeated Charge–Discharge Cycling

Takakazu Hirose, Kohta Takahashi, Takumi Matsuno, Yusuke Osawa, Masahiro Furuya, Reiko Sakai, Chinami Matsui and Hiroyuki Koide

Published 24 August 2020 ? ? 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited
Journal of The Electrochemical SocietyVolume 167Number 12 

Abstract

Carbon-coated SiO (SiO–C), which is a high-capacity anode material, experiences a significant capacity drop in the initial charge–discharge cycles. In contrast, Li-doped SiO–C (Li–SiO–C), which has been recently developed, exhibits a significantly smaller capacity drop. To explain this difference, we performed a detailed investigation of the structures and phase changes associated with the charge–discharge cycling of these materials by comparing their Si structures and electronic states obtained from solid-state magic-angle spinning nuclear magnetic resonance and Si K-edge X-ray absorption fine structure measurements. The results show that, in the case of SiO–C, the Li4SiO4 generated during charge is partially decomposed during discharge in the initial charge–discharge cycles. These generation and decomposition behaviors are most intense during the first 20 cycles. We believe that this phenomenon is the cause of the increased irreversible capacity observed in the initial cycles of SiO–C. In addition, we confirmed that Li2SiO3, a component of Li–SiO–C, is relatively stable electrochemically, although some of it gradually converts into Li4SiO4 during charge–discharge cycling. The presence of Li2SiO3 at the outset implies that less Li4SiO4 is generated during charging compared to SiO–C, which we believe explains the lack of a significant capacity drop in the initial cycles of Li–SiO–C.

下載文獻原文

Hirose_2020_J._Electrochem._Soc._167_120523.pdf

2020年08月26日

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信越化學-反復充放電循環過程中碳包覆SiO和鋰摻雜碳包覆SiO的結構和相變的比較

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